A Torque Ripple Suppression Method for Low Speed ​​Direct Drive Permanent Magnet Motor Servo System

Abstract

The invention discloses a torque pulsation restraining method of a low-speed direct-drive permanent magnet motor servo system, and belongs to the technical fields of power generation, power transformation and power distribution. According to the method, a virtual cogging torque which is distributed along the circumference of the axis section of the motor and is far larger than the actual cogging torque in amplitude is constructed by utilizing a quadrature axis current. The virtual cogging torque and the actual cogging torque are synthesized, so that only a unique and controllable positioning point is formed in one circle of a motor rotor; and the point is moved at a given speed of the motor, and a virtual damping item which is in negative correlation with the rotating speed error and capable of eliminating inherent oscillation of the rotating speed is introduced, so as to form a rotating speed controller to realize closed-loop control. According to the method disclosed by the invention, when the motor is driven, torque pulsation caused by cogging torque can be inhibited by redundant positioning point elimination and the damping items at low speed and even extremely low speed, the problem of crawling is solved, and a controller integral link causing compensation lag is eliminated, so that the control precision, the response speed and the robustness of the direct-drive servo system are improved.

Description

technical field [0001] The invention discloses a method for suppressing torque ripple of a low-speed direct-drive permanent magnet motor servo system, and particularly relates to a method capable of suppressing the speed crawling problem caused by cogging torque at low or even extremely low speeds, belonging to power generation , Power transformation, power distribution technology to reduce the torque ripple, control the technical field of torque ripple. Background technique [0002] With the rapid development of automatic control theory, microelectronics technology and computer technology, permanent magnet motor servo system is widely used in many fields such as national economy and national defense construction. Generally speaking, conventional servo systems mostly use the "AC motor + reducer" method to drive low-speed loads, but because of the existence of the reducer, there is a transmission error between the motor output shaft and the load, and the control accuracy is d...

AI Technical Summary

Problems solved by technology

However, the adoption of the direct drive solution brings convenience and higher performance but also brings new problems: in the direct drive servo system, the speed of the motor is the speed of the load, so the motor must inevitably run at a low speed. Many special problems often arise in

[0005] Weakening the influence of cogging torque can mainly start from two aspects: the first is to improve the distribution of the air gap magnetic field through the design of the motor structure, so as to achieve the purpose of weakening the amplitude of the cogging torque, but due to various conditions, especially Due to the structural constraints of different types of motors, the reduction of the positioning torque is limited. Changing the motor body will affect the no-load potential and power output capability of the motor and increase the manufacturing cost; the second is to compensate the stator through the optimal design of the motor control strategy. For the torque ripple generated by cogging, although the common compensation method can significantly improve the performance at medium and low speeds, due to the limitation of the resolution of the encoder, the motor will still vibrate and crawl when the speed is lower, especially for the aviation field For direct drive servo motors whose lower cogging torque is significantly larger than that of conventional motors, the direct torque compensation method has a limited effect on weakening the large cogging torque. control requirements

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